Currently the following method is known as a method for controlling a communication quality for every service in a packet communication network such as the Internet. The method includes temporarily queuing packets in a queue when relaying packets from by a router or the like, and controlling a rate or timing for fetching the packets from the queue. Examples of this control method include a method based on DiffServ that is normally incorporated into a TCP/IP (see Patent Document 1).
Another method is known for controlling an absolute band allocation amount while securing a communication quality to some extent by preparing a plurality of paths different in quality to a single destination in a network, e.g., a shortest-distance path and a bypass path, and by preferentially using one of the paths according to a service (see Patent Document 2).
Patent Document 1: Japanese Patent Application Laid-open No. 2001-197110
Patent Document 2: Japanese Patent Application Laid-open No. 2001-60966